\begin{table}%t4
   %\centering
\par
      \caption {Best-fitting models and X-ray fluxes at Earth for the brightest early-type stars in Westerlund~2. For each parameter, the lower and upper limits of the~90\% confidence interval (derived from the {\sc error} command under XSPEC) are noted as indices and exponents, respectively. The normalisation factors are defined as $10^{-14}\int n_{\rm e} n_{\rm H} {\rm d}V/4\pi D^2$, 
      where~$D$, $n_{\rm e}$ and $n_{\rm H}$ are respectively the distance to the source (8~kpc), the electron and proton density of the emitting plasma. Abundances were fixed to solar except for the WR stars (for more details, see text).
         \label{spec}}
     %\centering
\par
         \begin{tabular}{l cccccccc}
            \hline\hline
Star &  Obs & $N_{\rm int}^{\rm H}$ & $N^{\rm H}$ & ${\it kT}$ & Norm & $\chi^2_{\nu}$ (d.o.f.) & $f_{\rm X}^{\rm abs}$ & $L_{\rm X}^{\rm unabs}$\\
&     & $10^{22}$~cm$^{-2}$ & $10^{22}$~cm$^{-2}$  & keV   & $10^{-3}$~cm$^{-5}$         & & $10^{-13}$~erg~cm$^{-2}$~s$^{-1}$ & $10^{33}$~erg~s$^{-1}$  \\
            \hline
%\vspace*{-0.3cm}&\\
WR20a & Obs 1& 1.13& $\rm 1.53_{1.20}^{1.89}$ & $\rm 0.87_{0.24}^{1.04}$ & $\rm 1.57_{0.98}^{16.7}$ &  & & \\
%\vspace*{-0.3cm}&\\
 & & & $\rm 5.74_{1.89}^{14.6}$ & $\rm 1.96_{0.87}^{6.38}$ & $\rm 1.07_{0.29}^{10.7}$ & 1.15 (33)& 4.51& 4.95\\
%\vspace*{-0.3cm}&\\
WR20a & Obs 2& 1.13& $\rm 1.63_{1.40}^{1.92}$ & $\rm 0.42_{0.32}^{0.50}$ & $\rm 4.96_{3.04}^{10.9}$ &  & & \\
%\vspace*{-0.3cm}&\\
 & & & $\rm 5.48_{3.92}^{7.27}$ & $\rm 1.30_{1.16}^{1.52}$ & $\rm 2.61_{1.69}^{3.87}$ & 1.26 (97)& 4.10& 4.88\\
%\vspace*{-0.3cm}&\\
WR20a & Obs 3& 1.13& $\rm 1.93_{1.62}^{2.24}$ & $\rm 0.35_{0.29}^{0.43}$ & $\rm 9.60_{4.43}^{21.6}$ & & & \\
%\vspace*{-0.3cm}&\\
 & & & $\rm 3.28_{2.40}^{4.53}$ & $\rm 1.55_{1.39}^{1.75}$ & $\rm 1.88_{1.44}^{2.53}$ & 1.02 (119)& 5.04& 5.69\\
%\vspace*{-0.3cm}&\\
WR20b & Obs 1& 1.04 & $\rm 1.23_{0.67}^{1.88}$ & $\rm 3.62_{2.44}^{8.05}$ & $\rm 0.26_{0.18}^{0.38}$ & 1.24 (24)& 2.06& 1.88\\
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WR20b & Obs 2& 1.04& $\rm 2.18_{1.67}^{2.86}$ & $\rm 2.47_{1.94}^{3.13}$ & $\rm 0.41_{0.32}^{0.58}$ & 1.30 (35)& 1.97& 1.77\\
%\vspace*{-0.3cm}&\\
WR20b & Obs 3& 1.04& $\rm 1.03_{0.67}^{1.48}$ & $\rm 5.21_{3.70}^{6.72}$ & $\rm 0.22_{0.18}^{0.28}$ & 1.97 (38)& 2.29& 2.05\\
%\vspace*{-0.3cm}&\\
MSP18 & Obs 1& 0.88& $\rm 0._{0.}^{0.18}$ & $\rm 3.24_{2.53}^{4.18}$ & $\rm 0.31_{0.28}^{0.36}$ & 0.92 (18)& 2.88& 3.70\\
%\vspace*{-0.3cm}&\\
MSP18 & Obs 2& 0.88& $\rm 0._{0.}^{0.13}$ & $\rm 3.30_{2.81}^{3.64}$ & $\rm 0.27_{0.26}^{0.30}$ & 1.10 (59)& 2.54& 3.24\\
%\vspace*{-0.3cm}&\\
MSP18 & Obs 3& 0.88& $\rm 0._{0.}^{0.11}$ & $\rm 3.04_{2.65}^{3.43}$ & $\rm 0.32_{0.31}^{0.36}$ & 1.00 (56)& 2.88& 3.78\\
%\vspace*{-0.3cm}&\\
MSP167 & Obs 1& 0.98& $\rm 0.35_{0.}^{0.88}$ & $\rm 1.58_{1.07}^{2.27}$ & $\rm 0.11_{0.08}^{0.19}$ & 1.02 (12)& 0.52& 0.77\\
%\vspace*{-0.3cm}&\\
MSP167 & Obs 2& 0.98& $\rm 0._{0.}^{0.22}$ & $\rm 2.32_{1.91}^{2.72}$ & $\rm 0.10_{0.09}^{0.12}$ & 1.95 (21)& 0.72& 1.10\\
%\vspace*{-0.3cm}&\\
MSP167 & Obs 3& 0.98& $\rm 0.68_{0.}^{1.15}$ & $\rm 1.28_{0.91}^{2.32}$ & $\rm 0.16_{0.09}^{0.28}$ & 0.95 (11)& 0.56& 0.78\\
%\vspace*{-0.3cm}&\\
MSP188 & Obs 1& 0.96& $\rm 0.45_{0.23}^{0.69}$ & $\rm 1.22_{1.00}^{1.40}$ & $\rm 0.24_{0.20}^{0.33}$ & 1.56 (26)& 0.88& 1.51\\
%\vspace*{-0.3cm}&\\
MSP188 & Obs 2& 0.96& $\rm 0.36_{0.}^{0.52}$ & $\rm 1.33_{1.20}^{1.86}$ & $\rm 0.22_{0.16}^{0.26}$ & 0.73 (33)& 0.88& 1.49\\
%\vspace*{-0.3cm}&\\
MSP188 & Obs 3& 0.96& $\rm 0.70_{0.56}^{0.84}$ & $\rm 0.97_{0.84}^{1.09}$ & $\rm 0.30_{0.25}^{0.38}$ & 1.52 (30)& 0.74& 1.33\\
%\vspace*{-0.3cm}&\\
HD~90273 & Mgd& 0.22& $\rm 0.01_{0.}^{0.38}$ & $\rm 0.41_{0.22}^{0.52}$ & $\rm 0.02_{0.}^{0.17}$ & 0.88 (33)& 0.16& 0.28\\
%\vspace*{-0.3cm}&\\
MSP157 & Mgd& 0.92& $\rm 0._{0.}^{0.51}$ & $\rm 1.53_{1.08}^{1.92}$ & $\rm 0.010_{0.}^{0.018}$ & 0.97 (8)& 0.057& 0.12\\
%\vspace*{-0.3cm}&\\
MSP165 & Mgd& 1.08& $\rm 1.77_{1.29}^{2.48}$ & $\rm 0.28_{0.20}^{0.38}$ & $\rm 1.66_{0.}^{13.2}$ & 0.59 (10)& 0.088& 0.20\\
%\vspace*{-0.3cm}&\\
MSP175 & Mgd& 0.91& $\rm 1.31_{1.18}^{1.88}$ & $\rm 0.21_{0.14}^{0.28}$ & $\rm 2.25_{0.}^{59.8}$ & 1.20 (15)& 0.057& 0.18\\
%\vspace*{-0.3cm}&\\
MSP183 & Mgd& 1.03& $\rm 0.56_{0.36}^{0.85}$ & $\rm 0.63_{0.45}^{0.82}$ & $\rm 0.10_{0.}^{0.25}$ & 0.94 (20)& 0.14& 0.45\\
%\vspace*{-0.3cm}&\\
MSP203 & Mgd& 0.95& $\rm 0.19_{0.}^{0.47}$ & $\rm 0.99_{0.74}^{1.14}$ & $\rm 0.03_{0.02}^{0.05}$ & 1.09 (21)& 0.11& 0.32\\
%\vspace*{-0.3cm}&\\
MSP263 & Mgd& 1.09& $\rm 1.09_{0.62}^{1.65}$ & $\rm 0.31_{0.18}^{0.53}$ & $\rm 0.25_{0.}^{5.98}$ & 0.89 (7)& 0.034& 0.12\\
%\vspace*{-0.3cm}&\\
Src 2  & Mgd& 1.08& $\rm 1.42_{0.71}^{1.71}$ & $\rm 0.39_{0.33}^{0.68}$ & $\rm 0.40_{0.}^{0.77}$ & 1.20 (16)& 0.088& 0.19\\
            \hline
         \end{tabular}
   \end{table}